In a previously proposed procedure for vaporizing a substance by a hot melt for the purpose of treating the melt with the vaporized substance, the melt is charged into a tiltable reaction vessel and the substance to be vaporized is accommodated in a chamber which communicates with the reaction space of the vessel through openings. In order to initiate the vaporization of the substance, the reaction vessel is tilted whereby the substance to be vaporized is dipped under the surface of the melt. The speed of the vaporization is controlled by the openings of the chamber containing the substance. This procedure requires a first tilting movement of the reaction vessel for the filling of the metal melt into the vessel and a second tilting movement for moving the vessel into an upright position and thus the initiation of the vaporization of and treatment with the substance. A third tilting movement is necessary after the treatment in order to pour the treated melt into another vessel for shipping or further processing. It will be appreciated that the numerous tilting movements required by this procedure seriously limit the number of treatments which can be carried out per time unit. The output is thus very low.
According to another procedure for treating metal melts with vaporizable substances, it has been suggested to pour the melt into a ladle which can be closed by a plug. The substance to be vaporized is then dipped or immersed into the melt containing ladle. This procedure is rather cumbersome and is unsuitable, if not impossible, for the treatment of a metal melt with unalloyed magnesium. This is so because the course of the reaction can not be properly controlled.
It has also been suggested to carry out the treatment in an upright reaction vessel wherein the substance to be vaporized is initially separated from the reaction space of the vessel by a plug-like closure arrangement. The vaporization and thus the treatment are then initiated by lifting off or removing the closure arrangement. However, this prior art procedure is again unsatisfactory in that it does not render it possible satisfactorily to control the course of the treatment. This procedure is therefore not usable for the treatment with unalloyed magnesium.
According to a more recent proposal, it has been suggested to arrange a refractory intermediate wall or bottom at a predetermined distance above the bottom of the ladle or reaction vessel. According to this proposal, however, no chamber proper is provided for the vaporizable substance which has openings for the passage of the melt and for the controlled exit of the vapor bubbles of the vaporized substance, such as magnesium. This latter procedure is therefore also unsuitable for the treatment of a metal melt with unalloyed magnesium as the course of the reaction cannot satisfactorily be controlled.